Titrimetric and spectrophotometric determination of chlorhexidine digluconate in tooth pastes

New titrimetric and spectrophotometric methods for the fast determination of chlorhexidine digluconate (CHG) are described. The titrimetric determination is based on the precipitation of CHG as a 1 : 1 complex with Cu2+-ions and EDTA back-titration of the non-bonded Cu2+-ions without separating the precipitate. The spectrophotometric determination is based on the formation of a soluble CHG associate with dodecylsulphate (DDS) in a mixed medium of DDS-H2SO4-propanol, Both methods are applied to tooth pastes. When analysing a series of identical samples, the coefficient K (absorption of 1 g of the matrix) could be determined. Standard tooth pastes and corresponding placebo-compositions (containing all components except CHG) were specially prepared for the investigations and for estimating the accuracy of the methods.